fix(morello): add platform-specific power domain functions

Commit 4d8c18196378824e388cf31ef991ba8fbbb09cbf added a redistributor
power off to resolve an error on N1SDP/Morello. Prior to this fix,
turning off both cores in a cluster would cause a hang when powering
back on either core. This change introduced issues on other platforms
with a different GIC implementation, and was reverted in commit
60719e4e0965aead49d927f12bf2a37bd2629012.

This commit uses the previous fix in platform-specific implementations
of power domain off/suspend functions.

Signed-off-by: Werner Lewis <werner.lewis@arm.com>
Change-Id: Ib7689a5e08ada3862406fa92019a6f0bcfb48d79
diff --git a/plat/arm/board/morello/morello_bl31_setup.c b/plat/arm/board/morello/morello_bl31_setup.c
index cef42f4..e13a38b 100644
--- a/plat/arm/board/morello/morello_bl31_setup.c
+++ b/plat/arm/board/morello/morello_bl31_setup.c
@@ -12,6 +12,7 @@
 #include <services/arm_arch_svc.h>
 
 #include "morello_def.h"
+#include "morello_private.h"
 #include <platform_def.h>
 
 #ifdef TARGET_PLATFORM_SOC
@@ -33,6 +34,8 @@
 
 const plat_psci_ops_t *plat_arm_psci_override_pm_ops(plat_psci_ops_t *ops)
 {
+	ops->pwr_domain_off = morello_pwr_domain_off;
+	ops->pwr_domain_suspend = morello_pwr_domain_suspend;
 	return css_scmi_override_pm_ops(ops);
 }
 
diff --git a/plat/arm/board/morello/morello_pm.c b/plat/arm/board/morello/morello_pm.c
new file mode 100644
index 0000000..dda006e
--- /dev/null
+++ b/plat/arm/board/morello/morello_pm.c
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2023, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <lib/psci/psci.h>
+#include <plat/arm/common/plat_arm.h>
+#include <plat/arm/css/common/css_pm.h>
+
+#include "morello_private.h"
+
+/*******************************************************************************
+ * Morello specific functions called when turning off or suspending a power
+ * domain. Both additionally disable the GIC redistributor interface as cores
+ * are disabled to let cluster-PPU state transition to completion when a
+ * cluster is powered down.
+ ******************************************************************************/
+void morello_pwr_domain_off(const psci_power_state_t *target_state)
+{
+	css_pwr_domain_off(target_state);
+	plat_arm_gic_redistif_off();
+}
+
+void morello_pwr_domain_suspend(const psci_power_state_t *target_state)
+{
+	css_pwr_domain_suspend(target_state);
+	plat_arm_gic_redistif_off();
+}
diff --git a/plat/arm/board/morello/morello_private.h b/plat/arm/board/morello/morello_private.h
new file mode 100644
index 0000000..ea2fce9
--- /dev/null
+++ b/plat/arm/board/morello/morello_private.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2023, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef MORELLO_PRIVATE_H
+#define MORELLO_PRIVATE_H
+
+#include <lib/psci/psci.h>
+
+void morello_pwr_domain_off(const psci_power_state_t *target_state);
+void morello_pwr_domain_suspend(const psci_power_state_t *target_state);
+
+#endif /* MORELLO_PRIVATE_H */
diff --git a/plat/arm/board/morello/platform.mk b/plat/arm/board/morello/platform.mk
index 0f0cabb..0ae7693 100644
--- a/plat/arm/board/morello/platform.mk
+++ b/plat/arm/board/morello/platform.mk
@@ -49,6 +49,7 @@
 				${INTERCONNECT_SOURCES}			\
 				${MORELLO_GIC_SOURCES}			\
 				${MORELLO_BASE}/morello_bl31_setup.c	\
+				${MORELLO_BASE}/morello_pm.c		\
 				${MORELLO_BASE}/morello_topology.c	\
 				${MORELLO_BASE}/morello_security.c	\
 				drivers/arm/css/sds/sds.c